Operational research and numerical analysis are very important, especially operational research, with great probability. Some problems in operational research, such as planning, graphics and network problems, can be completely solved by EXCEL, so you should be proficient in Excel.

In addition, it is necessary to master the knowledge of mathematical statistics, and it is recommended to read more multivariate statistical analysis, time series analysis and regression analysis, and experimental design. If Markov model is involved, simply look at stochastic process, and the corresponding software is SPSS and SAS.

Other models can be processed in C language or MATLAB, giving you an experience. When choosing a programmer, you must also choose someone who is good at mathematics. Last time our group lost the election, we chose a person who was not good at math but was good at programming.

You still have a long time in the game. I recommend reading Mathematical Model by Jiang Qiyuan and Xie Jinxing.